| 摘要 |
PURPOSE:To obtain a semiconductor substrate having the following layers in a deep position with good reproducibility, by bonding a second thin semiconductor plate to a first thin semiconductor plate, in which an Si3N4 layer is formed and impurities are introduced in the layer, performing heat treatment, and forming an Si3N4 layer and an impurity diffused layer, which is formed so as to hold said layer and adjacent to said layer. CONSTITUTION:On one surface of an N-type first Si substrate 1, an Si3N4 film 2 is deposited. Then, impurity ions such as GA are implanted in the film 2. A second Si3N4 film 4 is formed on the film 2 by the similar way. The surface of the film 3 is finished in a mirror surface so that surface roughness is 500Angstrom or less. Then the surface is sufficiently washed by clean water and then dried at a temperature of 100 deg.C or less. Thereafter the back surface of an N-type second Si substrate 4 is finished so as t have a mirror surface by the similar way. The substrate 4 is closely contacted with the film 3. Heat treatment is performed at 1,000-1,200 deg.C. The substrates 1 and 4 are bonded through an Si3N4, in which the films 2 and 3 are bonded, and a desired semiconductor substrate 6 is obtained. Then the substrate 6 is heat-treated at about 1,200 deg.C, and P-type impurity diffused layers 7 are formed on both sides of the film 5. |
